2 pints equals 1 quart. So, if you convert the 2 pints into quarts, you get 6 quarts all together. Then, you just subtract 1 quart (the 2 pints) from the 5 quarts and you get 4 quarts! I hope it helps!! <3
EXPLANATION: 1) Know that there are 2 pints in 1 Quart 2) Thomas started with 5 quarts 3) 5 quarts = 10 pints 4) 10 pints- 2pints = 8pints 5) 8 Pints of milk are left.